An increasing number of censoring countries are using Deep Packet Inspection (DPI) to classify Internet traffic flows by protocol. While Tor uses bridge relays to get around a censor that blocks by IP address, the censor can use DPI to recognize and filter Tor traffic flows even when they connect to unexpected IP addresses.

Pluggable Transports help you bypass censorship against Tor.

Pluggable Transports (PT) transform the Tor traffic flow between the client and the bridge. This way, censors who monitor traffic between the client and the bridge will see innocent-looking transformed traffic instead of the actual Tor traffic. External programs can talk to Tor clients and Tor bridges using the pluggable transport API, to make it easier to build interoperable programs.

Learn more:

How to use PTs to bypass censorship

If connections to the Tor network are being blocked by your ISP or country, follow these instructions:

Become a PT bridge operator:

How to run PTs to help censored users

Anyone can set up a PT bridge server and help provide bandwidth to users who needs it. Once you set up a transport type, your bridge will automatically advertise support for the transport in its descriptor.

obfs4 is currently the most effective transport to bypass censorship. We are asking volunteers to run bridges for it. To learn how to run this transport, please visit the obfs4proxy wiki page.

Description: Is a transport that uses HTTP for carrying bytes and TLS for obfuscation. Traffic is relayed through a third-party server (Google App Engine). It uses a trick to talk to the third party so that it looks like it is talking to an unblocked server.

Undeployed PTs

StegoTorus

Description:is an Obfsproxy fork that extends it to a) split Tor streams across multiple connections to avoid packet size signatures, and b) embed the traffic flows in traces that look like HTML, JavasCript, or PDF. See its git repository.

Women's Sandal Platinum Dorian Spiga Via Dress Many are at the research phase now, so it's a perfect time to play with them or suggest new designs. Please let us know if you find or start other projects that could be useful for making Tor's traffic flows more DPI-resistant!